A medical imaging apparatus displays 3D image data based on volume data (3D (dimensional) data) collected by a medical image generating apparatus (medical diagnostic imaging apparatus). The medical image generating apparatus is, for example, an X-ray CT (computed tomography) scanner, an MRI (magnetic resonance imaging) apparatus, a diagnostic X-ray apparatus, and ultrasonic diagnostic equipment.
In recent years, techniques for 4D representation of pieces of 3D image data have been significantly advanced, the pieces each being generated in each of multiple time phases and generated by a medical image generating apparatus so as to have a high time resolution in addition to a three-dimensional spatial resolution. Accordingly, a region including movable parts (joints) such as a wrist and an ankle is scanned using, for example, an X-ray CT apparatus so as to generate pieces of CT volume data in multiple time phases while the movable parts are moved by bending, stretching, adduction, abduction, incycloduction, and excycloduction. Subsequently, movements of bones in or around the movable parts are shown to an operator by 4D representation provided using the pieces of 3D image data based on the pieces of the CT volume data. Such a technique has been generally used.
In a multi-slice X-ray CT apparatus, projection data can be obtained over a wider region by a single scan as detecting elements increase in number in a slicing direction (row direction) of a detector. In other words, dynamic volume scanning sequentially performed using the multi-slice X-ray CT apparatus can generate pieces of CT volume data in multiple time phases with a high frame rate. Thus, an operator can evaluate movements of bones through 4D representation within a unit time.
According to a disclosed technique in this technical field, a target bone (a bone region indicating a bone shadow region) is specified, position information on the bone in a first phase piece of volume data and position information on the bone in a second phase piece of volume data are determined, and 4D representation is provided based on the position information so as to show sequential changes of relative positions of other bones with respect to the target bone.
In 4D representation of prior art, however, many bones are moved in a complicated manner according to movements of movable parts, making it difficult for an operator to recognize the target bone from the 4D representation.
Moreover, in the 4D representation showing the sequential changes of the relative positions of the other bones with respect to the target bone, the target bone needs to be specified in advance on an image. Thus, if the target bone is not recognizable, the operator specifies target bone candidates one by one, lets the apparatus execute multiple 4D representations each showing sequential changes of relative positions of other bones with respect to the fixed target bone candidate, and has to visually confirm a target bone which is one of the target bone candidates while comparing the executed 4D representations.
An object of the present invention is to provide a medical imaging apparatus and a medical imaging method that can improve efficiency of image diagnosis performed by an operator in 4D representation.